Arable News

Straight flufenacet formulation to help in black-grass battle

New herbicide products containing a straight flufenacet formulation will be available for this autumn

New herbicide products containing a straight flufenacet formulation will be available for this autumn to give cereal growers much needed options to help control key weeds including resistant black-grass and annual meadow grass.Flufenacet has been available in mixture products for a number of years, however it has not been available on its own until now, says agrochemical company Certis. “Making flufenacet (500g/l) available as a straight product, ‘Sunfire’ and ‘System 50’ will give growers and advisers more flexibility to create bespoke programmes for each field on the farm,” comments arable product manager, Inez Cornell. “With no new active ingredients on the horizon, they will give growers a brand new tool for the fight against black-grass,” she adds. Black-grass resistance is an increasing problem in Europe, with more than ten countries reporting problems with control. And, because every plant has the potential to produce up to 2,000 seeds, minimising plant survival and seed return is critical, explains Inez. “Control of black-grass must be approached as an overall strategy, using every tool in the box – rotation, ploughing, delayed drilling, spring cropping and competitive varieties alongside herbicide options.” Dr Stephen Moss (left) has been studying resistant black-grass for more than 30 years and agrees that it’s absolutely critical for growers to get the best out of the existing herbicides we have available.“Resistance is present on virtually every farm in the UK where herbicides are used to control black-grass. In a black-grass survey conducted in 2013, 98 per cent of black-grass populations showed resistance to at least one herbicide,” says Dr Moss.“Although we have a good range of herbicides available for grass weed control, there is also some degree of cross-resistance to many of them, so there isn’t a simple solution to developing an effective herbicide programme,” he adds.The results of research show the overall trend is one of increasing herbicide resistance in post-emergence herbicides, with the efficacy of the ALS inhibitors (sulfonylureas) and ACCase inhibitors (fops and dims) showing the steepest decline in their ability to control black-grass.Control of black-grass must be approached as an overall strategy – rotation, ploughing, delayed drilling, spring cropping and competitive varieties alongside herbicide options.“Of all the pre-emergence herbicides tested in comparative container studies, flufenacet gave the greatest level of control across all populations of blackgrass; giving 99 per cent control of the highly susceptible standard population, 96 per cent control of the partially resistant population and 88 per cent control in the highly resistant Peldon population,” explains Dr. Moss.“It’s important to stress the importance of using pre-emergence herbicides, such as Sunfire and System 50, to help compensate for the declining control of post-emergence herbicides due to resistance,” he believes, especially as 97 per cent control needs to be achieved to stop black-grass populations from increasing.The key point to come out of research is that, of all the active ingredients tested, flufenacet is less affected by resistance. On a practical level this means there is a much smaller drop in the year-on-year efficacy of flufenacet (< 0.8 per cent per year) and less likelihood of selecting for resistance, in spite of the fact flufenacet is being used widely already.“The reason for this is that flufenacet tends to be used alongside other herbicides and those other herbicides are not acting in exactly the same way as flufenacet. So, by using a range of different modes of action, you can actually slow up the development of resistance,” explains Dr Moss.“The emphasis now must be on a more rational use of pre-em herbicides in combination with non-chemical methods to control black-grass,” he says. “Flufenacet, the active ingredient in Sunfire and System 50, should be seen as an essential component of any pre-em programme aimed at controlling resistant black-grass.”Inez concludes that Certis will be supporting a number of tank mixing options for Sunfire and System 50, which can be applied to winter wheat and winter barley crops, up to GS23 or before December 31st in the year of planting.